Ultrasonic measurement of optic nerve sheath diameter in elderly patients with craniocerebral injury.

OBJECTIVE: To explore the application value of ultrasonic measurement of optic nerve sheath diameter in elderly patients with craniocerebral injury. METHODS: 86 cases of elderly patients with craniocerebral injury treated in our hospital between January 2017 and December 2018 were included, all of whom had the invasive monitoring of intracranial pressure (ICP) and optic nerve sheath diameter (ONSD) in ultrasonic testing. According to ICP measurement results, patients were divided into a normal ICP group (n = 44) and an increased ICP group (ICP ≥ 20 mmHg stood for increased ICP, n = 42). Gender, age, systolic blood pressure, blood glucose, hospital stay, oxyhemoglobin saturation, ISS score, ONSD value, hematoma type, primary injury, associated injury and complications of the patients were compared. RESULTS: The univariate analysis showed that the systolic blood pressure in the ICP increased group was significantly decreased while the blood glucose, ISS and ONSD values showed significant increase (P < 0.05). The multivariate analysis showed that associated injury, systolic blood pressure and ONSD value had a significant influence on the increase of intracranial pressure (all P < 0.05). ONSD is positively correlated with ICP (r = 0.855, P = 0.000). The areas of systolic blood pressure and ONSD value under the curve in diagnosis of increased intracranial pressure in elderly patients with craniocerebral injury were 0.717 and 0.780, respectively. When the ONSD value was 4.90 mm, the area under the curve was 0.780, the sensitivity and specificity were 89.00% and 91.00%, respectively. When the ONSD value predicted that the critical value of good/poor prognosis of patients was 4.70 mm, the area under the curve was 0.796, the sensitivity was 91.00%, and the specificity was 90.00%. CONCLUSION: Ultrasound measurement of optic nerve sheath diameter can diagnose the increase of intracranial pressure in elderly patients with craniocerebral injury, and can better predict the prognosis.

Multimode Nonlinear Coupling Induced by Internal Resonance in a Microcantilever Resonator.

Coupled resonators represent a generic model for many physical systems. In this context, a microcantilever is a multimode resonator clamped at one end, and it finds extensive application in high-precision metrology and is expected to be of great potential use in emerging quantum technologies. Here, we explore the microcantilever as a flexible platform for realizing multimode nonlinear interactions. Multimode nonlinear coupling is achieved by (1:2) internal resonance (IR) and parametric excitation with efficient coherent energy transfer. Specifically, we demonstrate abundant tunable parametric behaviors via frequency and voltage sweeps; these behaviors include mode veering, degenerate four-wave mixing (D4WM) with satellite resonances, partial amplitude suppression, acoustic frequency comb (AFC) generation, mechanically induced transparency (MIT), and normal-mode splitting. The experiments depict a new scheme for manipulating multimode microresonators with IR and parametric excitation.

Plasmonic Microcantilever with Remarkably Enhanced Photothermal Responses.

Plasmonic nanostructures exhibit abundant optoelectronic properties. We explore here the technological potentials of plasmonic nanostructures as active component to actuate microcantilever sensors. We find that the photothermal excitation of microcantilevers can be greatly enhanced by Au nanoparticle (NPs). A detailed investigation reveals that the enhancement is wavelength dependent and can be attributed to selective excitation of localized surface plasmon resonance (LSPR). The associated effects are discussed based on a thorough examination of the geometric aspects of Au NPs, microcantilever lengths, and incident optical power. Some technological advantages offered by this method are also discussed.

Polarization Enhanced Charge Transfer: Dual-Band GaN-Based Plasmonic Photodetector.

Here, we report a dual-band plasmonic photodetector based on Ga-polar gallium nitride (GaN) for highly sensitive detection of UV and green light. We discover that decoration of Au nanoparticles (NPs) drastically increases the photoelectric responsivities by more than 50 times in comparition to the blank GaN photodetector. The observed behaviors are attributed to polarization enhanced charge transfer of optically excited hot electrons from Au NPs to GaN driven by the strong spontaneous polarization field of Ga-polar GaN. Moreover, defect ionization promoted by localized surface plasmon resonances (LSPRs) is also discussed. This novel type of photodetector may shed light on the design and fabrication of photoelectric devices based on polar semiconductors and microstructural defects.

Microcantilever Actuation by Laser Induced Photoacoustic Waves.

We present here a combined theoretical and experimental investigation on effective excitation of microcantilever by using photoacoustic waves. The photoacoustic waves arose from a vibrating Al foil induced by an intensity-modulated laser. We demonstrate that, superior to photothermal excitation, this new configuration avoids direct heating of the microcantilever, thus minimizing undesired thermal effects on the vibration of microcantilever, while still keeps the advantage of being a remote, non-contact excitation method. We also measured the vibration amplitude of the microcantilever as a function of distance between the microcantilever and the Al foil and found that the amplitudes decay gradually according to the inverse distance law. This method is universal and can be adopted in bio-microelectromechanical systems (BioMEMs) for the detection of small signals where detrimental thermal effects must be avoided.